Testing of Smoking Articles

ABSTRACT

A smoking machine is disclosed for the automatic smoking of a smoking article. The smoking machine ( 10 ) includes a flexible seal ( 30 ) for occluding holes ( 40 ) in the smoking article ( 28 ) while the smoking article is smoked. This can allow “intensive” smoking tests to be carried out by occluding filter holes ( 40 ) in the smoking article.

The present invention relates to techniques for occluding holes in a smoking article in order to enable testing of the smoking article.

Regular testing of cigarettes on a mechanical smoking apparatus, or smoking machine, is an important part of any cigarette manufacturing process. A smoking machine serves to create a repeatable standardised environment for the analytical smoking of cigarettes. International and national standards, including ISO standard 3308 (2000), have been put in place for standardising the operation of smoking machines.

A smoking machine typically comprises at least one holder for a cigarette, and a puffing means for drawing air in controlled fashion through the cigarette in regular short puffs in order to smoke the cigarette.

Filter tipped cigarettes are often designed with a number of ventilation holes made in the paper surrounding the filter area. The object of these ventilation holes is to dilute the smoke product drawn by the smoker into the mouth and lungs. When the holes are blocked the delivery of tar, carbon monoxide, nicotine and other products is usually increased.

When analysing the smoke products of cigarettes it may be necessary to occlude all or part of the ventilation holes placed in the filter area. When this occurs the method is known as “intensive smoking” as mechanisms used to reduce tar and nicotine delivery are defeated.

A known technique for occluding filter ventilation holes when intensive smoking is to be performed involves wrapping self adhesive tape about the whole filter area before the cigarette is placed into a smoking machine. However this method suffers from the disadvantages that it is not reliably reproducible, has potential for affecting the composition of the smoke constituents and has a tendency to give smoke composition results with a large scatter. An additional disadvantage is that the process is very labour intensive, repetitive and the final result depends upon the diligence and skill of the taper.

According to one aspect of the present invention there is provided a smoking machine for smoking a smoking article, the smoking machine including a flexible seal for occluding holes in the smoking article while the smoking article is smoked.

Such a machine can provide a simple and reproducible way of occluding the holes in the smoking article when performing intensive smoking tests.

Preferably the seal is made from an elastomeric material. This can allow the seal to expand or to contract, which can assist in the fitting of the seal. Furthermore an elastomeric material may provide good occlusion of the holes. Suitable materials for the seal include synthetic or natural rubber. The seal is preferably impermeable to gas, to prevent gas being drawn through the seal.

Preferably the seal is arranged such that the seal can expand and/or contract. This can allow the seal to adopt a first position in which a smoking article can be inserted into the seal (i.e. in which there is a gap between the seal and the smoking article), and a second position in which the seal grips the smoking article. Preferably the seal does not require the use of release agents or lubricants between seal and smoking article in order to insert or remove the smoking article.

The seal may be part of an occluding device, and the occluding device may comprise a rigid part to which the seal is attached. This may assist in the fitting and handling of the seal. The rigid part may be tubular and at least part of the seal may be located inside the rigid part. In order to attach the seal to the rigid part, at least one end of the seal may have a lip which wraps around an end of the rigid part.

The occluding device may comprise a port for applying a pressure change to the seal. For example, the port may be couplable to a pump or venturi which may apply an increased pressure or a reduced pressure or a vacuum to the seal. The device may then be arranged such that the seal can expand or contract in response to the change in pressure. This can allow the seal to expand before a smoking article is inserted into the device, and to contract to fit or to grip the smoking article once it is inserted. This thus provides a simple and convenient way of fitting the seal to and removing it from the smoking article. If required, a releasable valve may be provided for holding the seal in the expanded or contracted state.

For example, an air gap may be provided between the rigid part and at least part of the seal, and the port may be coupled to the air gap. Applying a pressure change to the air gap via the port may then cause the seal to expand or to contract to allow fitting and removal of the seal.

Alternatively, other techniques may be used to expand or contract the seal; for example a mechanical actuator may be coupled to the seal to expand or contract the seal.

Any flexible seal may in time become worn or may develop leaks or faults. If a faulty seal is used in a smoking test this may compromise the results of the test. In order to detect leaks or faults in the seal material, the device may be coupled to a pressure, flow or vacuum sensing device. Any change in the pressure, flow or vacuum outside of certain thresholds may indicate that there is a leak or fault in the seal material. The faulty seal can then be replaced.

The seal is preferably arranged (when fitted) to cover at least some filter holes in a filter of the smoking article, in order to allow intensive smoking tests to be carried out. The seal may cover the whole filter, or the seal may cover the at least some filter holes but not the whole filter. The filter holes may be totally occluded or partially occluded.

In some embodiments of the invention the seal is part of a holder for holding the smoking article in a smoking machine. In this way the holder itself can occlude the holes in the smoking article. This can provide a simple and reproducible technique for occluding the holes in the smoking article when performing intensive smoking tests. The seal may be part of the smoking machine holder seals (which seals are provided in conventional smoking machines), or the seal may substitute the smoking machine holder seals.

In some other embodiments, the seal is removable from the smoking machine, and is arranged to be fitted to the smoking article before insertion of the smoking article into the smoking machine. For example, the seal may be fitted to the smoking article in a separate apparatus before the smoking article is inserted into the smoking machine. To assist in the fitting the seal may be part of an occluding device such as that described above.

The invention also provides a smoking arrangement comprising a smoking machine in any of the above forms, and a smoking article, wherein the seal is attached to the smoking article.

In some embodiments of the invention the seal is not part of the smoking machine as such, and is arranged to be fitted to the smoking article before insertion of the smoking article into the smoking machine, for example by means of a separate seal fitting apparatus.

Thus, according to another aspect of the invention, there is provided a smoking arrangement comprising:

-   -   a smoking machine for smoking a smoking article; and     -   a flexible seal for occluding holes in the smoking article while         the smoking article is smoked.

The smoking arrangement may further comprise a smoking article, and the seal may be attached to the smoking article.

Any of the features of the first aspect of the invention may also be applied to the second aspect.

The smoking machine or arrangement in any of the above forms may further comprise means for applying a change in pressure to the seal. Furthermore, the smoking machine or arrangement may further comprise a pressure, flow, or vacuum sensing device to detect leaks or faults in the seal.

The smoking machine or arrangement may further comprise means for storing a desired value of pressure, means for comparing a sensed value of pressure with the stored value, and means for providing an indication of a fault in the seal in dependence on a result of the comparison. This can allow an operator to be warned should a fault develop in the seal.

This important feature of the invention can also be provided independently, and thus, according to another aspect of the invention, there is provided apparatus for detecting a fault in a device for occluding holes in a smoking article, the device comprising a rigid part, a flexible seal and an air gap between the rigid part and the flexible seal, the apparatus comprising:

-   -   means for sensing a pressure of the air gap;     -   means for storing a predetermined value of pressure;     -   means for comparing a sensed value of pressure with the stored         value; and     -   means for providing an indication of a fault in the seal in         dependence on a result of the comparison.

Different brands of cigarettes may have ventilation holes in different places. For intensive smoking tests it is important to ensure that the seal is located over at least some of the ventilation holes. This problem is addressed in another aspect of the invention.

Thus, according to another aspect of the invention there is provided apparatus for fitting seals onto a smoking article, the apparatus comprising:

-   -   means for fitting a seal to a smoking article;     -   means for storing the position of ventilation holes in a smoking         article; and     -   means for adjusting the relative position of the seal and         smoking article in dependence on the stored positions before the         seal is fitted to the smoking article.

Corresponding methods are also provided. Thus, according to another aspect of the invention, there is provided a method of automatically smoking a smoking article in a smoking machine, the method comprising occluding holes in the smoking article by means of a flexible seal.

The method may further comprise the step of applying a pressure change to the seal thereby causing the seal to expand or to contract. The method may further comprise the step of sensing pressure, flow or vacuum applied to the seal to detect leaks or faults in the seal material.

The method may comprise the step of fitting the seal to the smoking article prior to insertion of the smoking article into the smoking machine.

Any feature of one aspect of the invention may be provided with any other aspect. Apparatus features may be provided as method features and vice versa.

Preferred features of the present invention will now be described, purely by way of example, with reference to the accompanying drawings, in which:

FIG. 1 shows a cigarette holder according to a first embodiment of the invention;

FIG. 2 shows a cigarette holder according to a second embodiment;

FIG. 3 shows a cigarette holder and occluding seal according to a third embodiment;

FIG. 4 shows in diagrammatic form a mechanism by which occluding devices in a fourth embodiment are inserted onto cigarettes;

FIG. 5 shows a cigarette holder and occluding seal according to the fourth embodiment;

FIG. 6 shows parts of a seal fitting mechanism; and

FIG. 7 shows an arrangement for detecting faulty seals.

OVERVIEW OF THE INVENTION

Currently, when intensive smoking is to be performed, filter ventilation holes in the cigarette are occluded by wrapping self adhesive tape about the whole filter area before the cigarette is placed into the smoking machine. However the following problems have been identified in this technique:

-   -   The self adhesive tape used may be supplied by any company that         makes such products. The exact formulation may vary between         companies and consistency in the efficacy of the various tapes         may vary.     -   The adhesive used on the tape may not fully bond with the filter         tip and may create leakage paths through to the ventilation         holes in a non-specific and random way. Unwanted dilution of the         cigarette smoke may then occur.     -   The adhesive used on such tapes usually requires pressure to         fully form a seal. Applying pressure to the filter substrate may         deform the filter under test and so influence the yield of smoke         components as the fibres of the filter are closed up. This again         introduces a variable to the analytical smoking process.     -   The adhesive used may have volatile components that are drawn         into the cigarette and contaminate the smoke stream that is         being analysed. Moreover the process of smoking may also         liberate elements of the adhesive which can effect the smoke         composition. The potential differences in adhesive composition         from various adhesive tape manufacturers introduce a random, and         unquantifiable, element into the smoking process.     -   The polymer tape used will also differ between manufacturers and         so may the gas permeability of the various tapes. If gas can         permeate through the tape, as some are designed to do, the         degree of occlusion of the ventilation holes can vary in a         non-specific manner.     -   Tapes are normally applied by hand and the reproducible         application of such tapes is difficult, especially as for normal         smoking experiments many cigarettes may require taping.     -   In taping cigarettes there must be no overlap of the ends of the         tape, otherwise, when fitted into a holder of a mechanical         smoking device, a small gap may appear between holder and         cigarette that allows air into the smoking machine, diluting the         smoke stream and again giving inconsistent results.     -   In attempting to produce perfect butt joints it is not unusual         to leave small gaps between the ends of the tape, again         providing a leakage path and a source of irreproducibility.     -   Punctures in the tape are not easily detected, yet any hole in         the occluding material will have a profound effect on the         measured yields of smoke components.

In embodiments of the present invention, elastomeric seals are used to occlude the ventilation holes in cigarettes for intensive smoking. A vacuum method of fitting is used to ensure that the seals are leak and puncture free.

In embodiments of the invention, seals, made from silicone rubber, neoprene or any other suitable elastic material are placed in a holder either by hand or loaded via a machine interface. One end, or both ends, of the seal material is fitted to the holder by means of a clamp or through stretching over a suitable retaining lip. The gap between seal and holder is then evacuated pulling the seal material into a tube of greater diameter than in the relaxed state. The process of evacuating the gap between holder and seal not only expands the seal, but also by using a vacuum, ensures that the seal material is free from pin holes and leaks. As the seal is pulled by vacuum the natural leak rate can be monitored by a suitable commercial pressure gauge and the measured leak rate compared with a leak free sample. Any deviation from the ideal leak rate indicates that the seal material is faulty and would not produce a reproducible seal around the cigarette.

Once the seal is stretched, the cigarette is placed into the seal so that the seal material covers the tip area, or the part of the tip area that includes the ventilation holes. The vacuum is then released and the elastomer then relaxes about the filter forming a leak free seal.

It can be seen that the seals used should be selected of a diameter that closely matches or is best suitable to the filter diameter; however a suitable system can be devised that uses common holders and a range of suitable seal diameters.

FIRST EMBODIMENT

In this embodiment the standard seal mechanism recommended for smoking mechanically, which typically includes between 3 and 4 labyrinth seals, is replaced by a holder that is essentially tube like in construction. As part of this tube like holder there is a side evacuation port. The tube is approximately the same length as the filter to be occluded.

FIG. 1 shows a cigarette holder according to the first embodiment. Referring to FIG. 1, cigarette holder 10 comprises smoking machine interface 12 and o-ring seals 14 which are used to interface the holder to a smoking machine (not shown). Filter pad holder 16 is attached to smoking machine interface 12, and the join is sealed with o-ring seal 18. Filter pad holder 16 holds a filter pad 20 which is used to filter smoke drawn from a cigarette. Inserted into the filter pad holder 16 is a special holder 22 which is tube-like in construction. The internal diameter of the holder 22 is slightly larger than the diameter of a cigarette 28 which is to be tested. The holder is sealed to the filter pad holder 16 by o-ring 24. A rubber bumper 26 provides a step against which a cigarette abuts when it is fully inserted into the holder 22.

An elastomeric seal 30 is located inside the holder 22. The seal 30 is tubular for most of its length, and at either end has lips that wrap around the extremities of the holder 22. The lips grip the holder and provide a seal thereto. On the inside of the holder there is an air gap 32 between the seal and the holder. An evacuation port 34 is provided in the holder, and is in communication with the air gap 32. The port 34 is connected to a vacuum pump 35 by means of the tube 36. A pressure sensing device 38 is connected in the tube 36 to sense the pressure in the tube.

The vacuum pump 35 is connected to a control unit 42, which controls the operation of the pump in accordance with a required smoking operation. The pressure sensor 38 is also connected to the control unit 42, so that the control unit can indicate when a faulty seal is detected.

In operation, when it is desired to smoke a cigarette 28 having filter holes 40, a vacuum is first applied to the port 34, and the elastomeric seal 30 is pulled out towards the walls of the holder 22. If the seal 30 fails to expand to the walls of the holder then the seal has become compromised and requires replacement. Similarly the pressure sensing device 38 (or alternatively a gauge detecting flow or vacuum in line with the evacuation port) can determine the integrity of the seal by determining the pressure between the seal 30 and the holder 22. Leaks can then be located by inspection and faulty seals replaced.

The cigarette 28 is then placed inside the holder 22 until the end butts up against the rubber bumper 26 inside the holder. The vacuum is then released and the occluding seal 30 grips the filter of the cigarette to be tested. The location of the seal 30 with respect to the filter holes 40 is such that the filter holes are occluded by the seal when the vacuum is released.

The cigarette 28 is firmly gripped by the elastomeric seal 30 without deforming the filter, yet forming an air tight seal. The seal 30 thus performs the dual task of occluding filter holes and forming a seal with the instrument, which seal would usually be provided by a series of labyrinths seals.

The cigarette can then be smoked by the smoking machine in a known manner. On completion of the smoking run the vacuum is again applied to release the seal ready for use in the next run.

The control unit 42 may be part of the smoking machine, and may co-ordinate operation of the pump with other functions of the smoking apparatus. For example, if cigarettes are loaded automatically into the holder 10, then the control unit 42 may operate the pump 35 so as to expand the seal 30 at the appropriate moment before the cigarette is inserted into the holder 10.

SECOND EMBODIMENT

In this embodiment the occluding seal is molded in shape to include one of the prescribed seals used to hold the cigarette in place in the ISO style holder. The holder is modified to include an oversized diameter tube the approximate length of the filter with an evacuation port that can be connected to a source of vacuum. This vacuum can be generated by pump, venturi effect or similar.

FIG. 2 shows a cigarette holder 50 according to the second embodiment. Parts of the holder 50 which are in common with the holder 10 in the first embodiment are given the same reference numerals and are not described further.

Referring to FIG. 2, cigarette holder 50 includes a special holder 52 attached to filter pad holder 16 and sealed thereto by means of o-ring seals 54 and 56. The holder 52 includes at one end a plurality of labyrinth seals 58, as would be present in a conventional cigarette holder for holding the cigarette. The holder 52 also includes a tubular portion extending along the axis of the cigarette 28. The tubular portion of the holder 52 is provided with elastomeric seal 60.

As in the first embodiment, the seal 60 is tubular for most of its length, and at its furthest end has a lip 62 which wraps around the extremity of the holder 52 so as to grip the holder and provide a seal. The other end of the elastomeric seal 60 is formed integrally with one of the labyrinth seals 58.

The tubular portion of the holder 52 is provided with an evacuation port 64.

In operation, before insertion of the cigarette 28, the occluding seal 60 is fitted into the holder seal stack 58, and the special holder 52 is fitted. The end of the occluding seal 60, which may be plain or castellated, is rolled over the end of the holder 52. The seal material is held in place by the action of the seal material gripping into a recess or gripping a larger diameter of the holder.

Vacuum is then applied to the evacuation port 64 and the seal 60 is drawn out toward the sides of the holder 52. The cigarette 28 is then inserted into the whole holder stack until it butts up against the bumper 26 at the inner face of the holder stack.

If the sleeve is not drawn out by the vacuum then there is a hole in the sleeve and it will have to be discarded and a new seal fitted. In addition the presence of a gauge measuring pressure and/or vacuum can detect minor leaks which will indicate that an individual seal is faulty and should be replaced.

The vacuum is then released. The seal relaxes about the filter thus closing the ventilation holes. The smoking process can now take place.

On termination of the smoking run—a feature of the smoking machine—the vacuum can again be applied and the used cigarette removed. The seal is then available for further tests.

THIRD EMBODIMENT

In a third embodiment the occluding seals are fitted to the cigarette under test in a separate apparatus designed specifically for the purpose. The apparatus is set such that when a cigarette is placed in the machine it reaches a stop that presents the filter so that when the occluding seal is fitted it starts at the exact position where the normal smoking machine seals commence and forms a butt joint with the existing seal. The extent of the seal is determined by the overall length of the filter under test and seal length is chosen on this basis. This stop is independent of the brand of cigarette used.

Seals are loaded into the mechanism either automatically or manually and through use of vacuum expansion to create a greater diameter than in the relaxed state. The cigarette is loaded into the holder and the vacuum released allowing the seal to contract and fit snugly about the filter.

The nature of the mechanism is such that the vacuum can be monitored to discover minor or major leakage through the occluding seals and give warning that the seal should not be used and should be replaced.

The cigarettes are removed and fitted to a standard cigarette holder as used in a smoking machine.

Once the article has been smoked the seal is discarded.

FIG. 3 shows a cigarette holder and occluding device in the third embodiment. In this embodiment the seal holder is of standard construction, and a separate occluding device is used to occlude the filter holes. In FIG. 3 parts of the first or second embodiments are given the same reference numerals and are not described further.

Referring to FIG. 3, a conventional cigarette holder 70 comprises a plurality of labyrinth seals 58 for gripping a cigarette 28 which has been inserted into the holder 70. A separate occluding device 72 which is essentially tubular in shape includes on the inside an elastomeric seal 74. The seal 74 is also tubular with lips at its extremity which wrap around and grip the ends of the occluding device 72. The occluding device 72 is provided with an evacuation port 76, which is connected to a vacuum pump 35 in the same way as described above with reference to the first and second embodiments. Alternatively, the occluding device 72 is fitted to the cigarette off-line in a separate apparatus before fitting to the standard holder, in a similar way to the fourth embodiment described below.

FOURTH EMBODIMENT

In a fourth embodiment the occluding seals are fitted to the cigarette under test in a separate apparatus designed specifically for the purpose. The position of the ventilation holes and extent of perforation is known and the length of seals that will cover the holes is chosen before fitment. In this design the holes are only covered and not the whole filter length. The apparatus is set such that when a cigarette is placed in the machine it reaches a stop that presents the filter ventilation holes such that when a seal is fitted it will cover all the holes. This stop is variable and can be set dependant upon the brand of cigarette used.

FIG. 4 shows in diagrammatic form the mechanism by which occluding devices in accordance with the fourth embodiment are inserted onto cigarettes. Each occluding device 80 includes on its inside an elastomeric seal 82 having lips which wrap around and grip the ends of the occluding device. The occluding device also includes an evacuation port 84 which allows the device to be connected to a vacuum when the device is being fitted to the cigarette.

Occluding devices 80 are loaded into the mechanism either automatically or manually to form a column of devices ready to be fitted. A device which is to be fitted is expanded through use of vacuum to a greater diameter than in the relaxed state. The cigarette is loaded into the apparatus and the vacuum released allowing the seal to contract and fit snugly about the filter in the region of the ventilation holes.

The nature of the mechanism is such that the vacuum can be monitored to discover minor or major leakage through the occluding seals and give warning that the seal should not be used and should be replaced.

The cigarettes are then removed and fitted to a standard cigarette holder as used in a smoking machine.

FIG. 5 shows a cigarette holder and occluding device once the cigarette has been inserted into the holder. Parts of the holder which are in common with previous embodiments are given the same reference numerals and are not described further.

Once the smoking run has been concluded the seals are discarded.

FIG. 6 shows some parts of the seal fitting mechanism in more detail. Referring to FIG. 6, a motor 90 is provided which can vary the position of variable stop 92 under control of control unit 94. Control unit 94 has a memory which stores the positions of ventilation holes in different brands of cigarettes. Before a cigarette is placed in the machine, the operator enters the brand of cigarette by means of keypad 96. Alternatively, if the cigarette is not of a brand recognised by control unit 94, the operator may enter the position of ventilation holes in the cigarette. The control unit 94 then adjusts the position of the stop 92 by means of motor 90 so that a seal, when fitted, will cover some or all of the ventilation holes.

As an alternative, instead of adjusting the position of the stop 92, the position of the seal when it is fitted to the cigarette could be adjusted.

Control unit 94 also controls operation of pump 98. Pump 98 applies a vacuum to the seal so as to expand it before a cigarette is inserted. Once a cigarette has been inserted the vacuum is released allowing the seal to contract and fit about the filter in the region of the ventilation holes.

Detection of Failed Seals

The detection of pin holes and other faults in the occluding membranes is of importance for obtaining consistent results during the smoking process. In particular where the occlusion of ventilation holes is part of a so called “intensive smoking” regime any path for air to be drawn into the smoking article at the point of ventilation will reduce the measured yields and underestimate the quantity of substances in the main stream smoke commonly grouped together under the label of “tar”. Overall this will result in high variability of results and doubt may be thrown on the validity of the results so obtained.

FIG. 7 shows an arrangement which can provide a simple check for pin holes and other faults in order to ensure that a consistent seal is made about the ventilation holes. This arrangement can be used with any of the embodiments described above, or indeed with seals which are designed for other purposes such as measuring pressure drop.

Referring to FIG. 7, occluding seal S1 is placed in its former or holder which is connected to a valve V1, pump P1 and vacuum gauge VG by means of tubing. In order to allow the cigarette to be inserted into the seal, the pump P1 is started and the valve V1 opened. This evacuates the connecting tubing and the surrounding area of the occluding membrane. The membrane S1 is pulled outwards increasing the aperture it has formed about the former or holder. This larger aperture allows the cigarette to be fitted into the seal.

The vacuum gauge VG indicates the pressure between the pump P1 and the flexible seal S1. The pressure can be indicated by means of analogue or digital reading and this can be compared with the expected vacuum of the pump and perfect seal. If desired, this comparison could be carried out by the operator. However, in the arrangement shown in FIG. 7, a failed seal detecting unit D is provided, which compares the actual pressure with a predetermined threshold value and provides an indication of a fault when the pressure is too high. For example, a visual or audible indication of a fault may be provided to warn the operator that the seal has failed. This ensures that “gross” faults are detected before the cigarette is fitted to the seal. If the pressure detected is acceptable, the cigarette is inserted into the seal and the valve V1 is closed.

During smoking of the cigarette, the pressure in the line S1, VG, V1 is measured continuously or continually. Since no seal line and seal will be entirely vacuum tight, there will be a slow increase in pressure (loss of vacuum). The rate of change of pressure can be calculated and compared against an expected leak rate for a defect free seal. In FIG. 7, this calculation is carried out by detecting unit D, and an indication of a fault is provided if the leak rate is too high. Again, a visual or audible indication may be provided to warn the operator that the seal has failed or is failing. In such a way the integrity of the occluding membrane can be verified to ensure that there is a more perfect smoking of the vent blocked cigarette.

While preferred embodiments have been described above, modifications are possible within the scope of the present invention. For example, in all of the above embodiments, rather than using a vacuum to withdraw the seal in order to allow insertion of a cigarette, the seal may have a relaxed state which is slightly larger than the cigarette, and an increased pressure may be applied to the seal so that it expands and occludes the filter holes. In this case the vacuum pump would be replaced by a pump which supplied an increased pressure.

For example, the seal may consist of a tube resembling a tyre inner tube having a valve connected to a pump. With a cigarette inserted into the holder, air is supplied to the tube via the value. The tube then expands to block the filter holes while the cigarette is being smoked. Once the test is completed the valve is released to allow the air to escape, thereby causing the tube to contract to its relaxed state in which the cigarette can be removed.

The present invention may be used to test smoking articles other than cigarettes, such as cigars and cigarillos. 

1-34. (canceled)
 35. A smoking machine for smoking a smoking article, the smoking machine including a flexible seal arranged to occlude at least some ventilation holes in a filter of the smoking article, the smoking machine being arranged to smoke the smoking article while the ventilation holes are occluded by the flexible seal.
 36. A smoking machine according to claim 35 wherein the seal is made from an elastomeric material.
 37. A smoking machine according to claim 35 wherein the seal is made from one of synthetic rubber and natural rubber.
 38. A smoking machine according to claim 35, wherein the seal is impermeable to gas.
 39. A smoking machine according to claim 35, wherein the seal can expand and contract.
 40. A smoking machine according to claim 39 wherein the seal can adopt a first position in which a smoking article can be inserted into the seal, and a second position in which the seal grips the smoking article.
 41. A smoking machine according to claim 35, wherein the seal does not require the use of release agents or lubricants between seal and smoking article.
 42. A smoking machine according to claim 35, wherein the seal is part of an occluding device, and the occluding device comprises a rigid part to which the seal is attached.
 43. A smoking machine according to claim 42, wherein the rigid part is tubular and at least part of the seal is located inside the rigid part.
 44. A smoking machine according to claim 43 wherein at least one end of the seal has a lip which wraps around an end of the rigid part.
 45. A smoking machine according to claim 42, wherein the occluding device comprises a port to allow a pressure change to be applied to the seal.
 46. A smoking machine according to claim 45, wherein the device is arranged such that the seal can expand and contract in response to the change in pressure.
 47. A smoking machine according to claim 45, wherein an air gap is provided between the rigid part and at least part of the seal the port being coupled to the air gap.
 48. A smoking machine according to claim 45, wherein the device is coupled to one of a pressure sensing device, flow sensing device, and vacuum sensing device to detect leaks or faults in the seal.
 49. A smoking machine according to claim 35 wherein the seal covers the whole filter.
 50. A smoking machine according to claim 35 wherein the seal covers at least some ventilation holes but not the whole filter.
 51. A smoking machine according to claim 35 wherein the ventilation holes are totally occluded or partially occluded.
 52. A smoking machine according to claim 35, wherein the seal is part of a holder for holding the smoking article in the smoking machine.
 53. A smoking machine according to claim 52 wherein the seal is part of the smoking machine holder seals.
 54. A smoking machine according to claim 52 wherein the seal substitutes the smoking machine holder seals.
 55. A smoking machine according to claim 35, wherein the seal is arranged to be fitted to the smoking article before insertion of the smoking article into the smoking machine.
 56. A smoking machine according to claim 35, further comprising an arrangement which applies a change in pressure to the seal.
 57. A smoking machine according to claim 35, further comprising a pressure sensing device to detect leaks or faults in the seal.
 58. A smoking machine according to claim 57, further comprising a store which stores a desired value of pressure, a comparator which compares a sensed value of pressure with the stored value, and an indicator which provides an indication of a fault in the seal in dependence on a result of the comparison.
 59. A smoking arrangement comprising: a smoking machine; a smoking article placed in the smoking machine for smoking by the smoking 20 machine; and a flexible seal attached to the smoking article for occluding ventilation holes in a filter of the smoking article while the smoking article is smoked, wherein the seal is part of an occluding device, and the occluding device comprises a rigid part to which the seal is attached.
 60. A method of automatically smoking a smoking article in a smoking machine, the smoking machine including a flexible seal, the method comprising occluding ventilation holes in a filter of the smoking article by means of the flexible seal, while the smoking article is being smoked.
 61. A method according to claim 60, further comprising the step of applying a pressure change to the seal thereby causing the seal to expand or to contract.
 62. A method according to claim 60, further comprising the step of sensing pressure, flow or vacuum applied to the seal to detect leaks or faults in the seal material. 